单项选择题

Social networking sites like Facebook and MySpace do not help you make more genuine close friends, according to a survey by researchers who have studied how the websites are changing the (1) of friendship networks. Although social networking on the Internet helps people to (2) hundreds or even thousands of acquaintances, the researchers believe that face to face (3) is nearly always (4) in forming truly close friendships. "Although the numbers of friends people have on these sites can be (5) , the actual number of close friends is (6) the same in the face to face real world," said Will Reader at Sheffield Hallam University.
Social networking websites such as Facebook, Bebo and MySpace have (7) rapidly in recent years. Previous research has suggested that a person’s (8) friendship group (9) of around 150 people, with five very close friends but larger numbers of people who we keep in touch with less (10) . This figure is so (11) that scientists have suggested it is determined by our cognitive (12) . Larger numbers just require too much brain effort to keep (13) . But Dr. Reader and his team have found that social networking sites do allow people to (14) this figure and broaden their (15) of nodding acquaintances because staying in touch online is easy. What social network sites can do is to decrease the cost of (16) and forming these social networks because we can post information to (17) people," he said.
But to (18) a real friendship we need to see that the other person is trustworthy. "We (19) time and effort in them in the hope that sometime they will help us out. It is a kind of (20) relationship," said Dr. Reader.

16（）

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